C96.6 Unifocal Langerhans-cell histiocytosis

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Eosinophilic granuloma
• Histiocytosis X, unifocal
• Histiocytosis X NOS
• Langerhans-cell histiocytosis NOS

Excludes1 (never code together)

• multifocal and multisysemic (disseminated) Langerhans-cell histiocytosis (C96.0)
• multifocal and unisystemic Langerhans-cell histiocytosis (C96.5)

Applies from C96 Other and unspecified malignant neoplasms of lymphoid, hematopoietic and related tissue

Excludes1 (never code together)

• personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues (Z85.79)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 21 — Lymphoma and Other Cancers
• CMS-HCC V22: HCC 10 — Lymphoma and Other Cancers
• RxHCC V08: HCC 21 — Lymphomas and Other Hematologic Cancers
• ESRD V24: HCC 10

MS-DRG index

Defines the logic of DRG(s) 642 in MDC 10.

Approximate ICD-9-CM (GEMs)

• 277.89 Other specified disorders of metabolism (approximate)

Code annotations containing back-references to C96.6

Back-references to C96.6

• Type 1 Excludes: C96.0 Multifocal and multisystemic (disseminated) Langerhans-cell histiocytosis ("unifocal Langerhans-cell histiocytosis (C96.6)")
• Type 1 Excludes: C96.5 Multifocal and unisystemic Langerhans-cell histiocytosis ("unifocal Langerhans-cell histiocytosis (C96.6)")
• Type 1 Excludes: D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissue ("eosinophilic granuloma (C96.6)")
• Type 1 Excludes: D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissue ("histiocytosis X, unifocal (C96.6)")
• Type 1 Excludes: D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissue ("Langerhans-cell histiocytosis NOS (C96.6)")
• Type 1 Excludes: D76 Other specified diseases with participation of lymphoreticular and reticulohistiocytic tissue ("Langerhans-cell histiocytosis, unifocal (C96.6)")
• Type 1 Excludes: E88 Other and unspecified metabolic disorders ("histiocytosis X (chronic) (C96.6)")
• Code First: N16 Renal tubulo-interstitial disorders in diseases classified elsewhere ("lymphoma (C81.0-C85.9, C96.0-C96.9)")

Back-references to C96

• Type 1 Excludes: C76 Malignant neoplasm of other and ill-defined sites ("malignant neoplasm of lymphoid, hematopoietic and related tissue (C81-C96)")
• Type 1 Excludes: C77 Secondary and unspecified malignant neoplasm of lymph nodes ("malignant neoplasm of lymph nodes, specified as primary (C81-C86, C88, C96.-)")
• Code Also: D59.39 Other hemolytic-uremic syndrome ("malignant neoplasm (C00-C96)")
• Code First: D84.81 Immunodeficiency due to conditions classified elsewhere ("malignant neoplasms (C00-C96)")
• Code First: E08 Diabetes mellitus due to underlying condition ("malignant neoplasm (C00-C96)")
• Code First: Z15.0 Genetic susceptibility to malignant neoplasm (", if applicable, any current malignant neoplasm (C00-C75, C81-C96)")

Diagnosis Index entries for C96.6

• Granuloma › bone › eosinophilic
• Granuloma › bone › lung
• Granuloma › eosinophilic
• Granuloma › eosinophilic › bone
• Granuloma › eosinophilic › lung
• Granuloma › lung (infectious) › eosinophilic
• Histiocytosis › Langerhans' cell NEC
• Histiocytosis › Langerhans' cell NEC › unifocal (X)
• Histiocytosis › mononuclear phagocytes NEC › Langerhans' cells
• Histiocytosis › X NEC
• Histiocytosis › X NEC › chronic
• Histiocytosis › X NEC › unifocal

Nearby codes

• C96.21 Aggressive systemic mastocytosis
• C96.22 Mast cell sarcoma
• C96.29 Other malignant mast cell neoplasm
• C96.4 Sarcoma of dendritic cells (accessory cells)
• C96.5 Multifocal and unisystemic Langerhans-cell histiocytosis
• C96.6 Unifocal Langerhans-cell histiocytosis (this code)
• C96.A Histiocytic sarcoma
• C96.Z Other specified malignant neoplasms of lymphoid, hematopoietic and related tissue
• C96.9 Malignant neoplasm of lymphoid, hematopoietic and related tissue, unspecified